The present invention relates generally to methods and apparatus for cooling sensors located in areas in which the sensors are subjected to temperature extremes, and more specifically relates to such methods and apparatus believed to have particular utility relative to sensors mounted in extreme temperature environments on aircraft.
In the design and evaluation of various types of equipment, such as, for example, aircraft (planes, missles, etc.); sensors, such as temperature sensors (or thermocouples), strain gauges, and fluctuating pressure or acoustic sensors may be placed upon an aircraft, such as either a prototype or a production aircraft, to evaluate actual conditions to which portions of the aircraft are subjected. This facilitates evaluation of the actual design relative to the conditions anticipated during the design process. For example, portions of an aircraft in the vicinity of the engine exhaust may be evaluated with thermocouples and acoustic sensors to determine the temperature and pressure or vibration to which the portions are subjected during operation of the aircraft. Such evaluation facilitates assuring the viability of the design.
A particular problem in this regard has been presented relative to certain sensors, such as acoustic sensors (generally known as "microphones") utilized in such an environment. In some applications, these acoustic sensors may be subjected to exceptional temperature loading; for example, 800 degrees fahrenheit or higher. In many cases, the temperature loading may exceed the normal thermal tolerance of the microphone or sensor. For example, microphones utilized for such tests typically have a thermal tolerance of approximately 500 degrees fahrenheit or less. As acoustic sensors utilized for such purposes are typically quite expensive, often costing several hundreds of dollars, the risk of damaging sensors through excessive heat loading in the environment in which they are placed has presented a significant and expensive problem in aircraft evaluation operations.
Additonally, sensors adapted for extreme high temperature environments typically use extremely expensive sensors, often costing on the orders of tens of thousands of dollars, but which exhibit a significant reduction in sensitivity. Accordingly, generally, the lower temperature environment that an acoustic sensor may be designed for, than a greater sensitivity may be maintained in the sensor.
Accordingly, the present invention provides a new method and apparatus for facilitating the placement of sensors, such as acoustic sensors in high temperature environments. The present invention also facilitates the use in high temperature environments of acoustic sensors having optimal sensitivity for the application in question.